Wave driven work extracting device

ABSTRACT

A work extracting device driven by the wave motion of a fluid comprising a first float, a cylinder, a piston slidably engaging the interior of the cylinder, a piston rod extending from the piston and pivotally coupled to the first float, and a second float connected to the first float. The first float has a density suitable for floating and moves in response to wave motion. The cylinder is pivotally mounted to the second float. The first and second floats are part of a Hagen array of floats. The first float has an arm extending a distance beyond the point of connection of the first and second floats. The piston rod is pivotally mounted generally about the end of the arm.

RELATED APPLICATIONS

This is a divisional application of co-pending application Ser. No.515,471, filed on July 20, 1983.

TECHNICAL FIELD

The present invention relates to apparatus for extracting work from thewave motion of a fluid.

BACKGROUND ART

Many countries throughout the world have a vital need for obtainingfresh water from sea water. Typically, island-countries require eitherthe distillation of sea water or the importation of fresh water in orderto supply their needs. In many parts of the United States, there arecritical water shortages that could be quickly remedied through thedistillation of adjacent sea water. However, it has seldom been thoughtto be cost effective to distill sea water through presently availabletechniques. As a result, water importation into areas of need has beenthe typical solution for providing fresh water.

There are many areas of the world that have been relying on the use ofoil or natural gas to obtain fresh water. For example, in the U.S.Virgin Islands, about half of the fresh water supply is produced throughoil-fired stills. The other half of their fresh water supply is bargedfrom Puerto Rico. These methods of obtaining fresh water are incrediblyexpensive.

Under presently available techniques, it is possible to distill seawater through application of wave energy. However, under suchtechniques, the wave energy is used to generate electricity which is, inturn, used to provide heat to the still. (See, for reference, U.S. Pat.No. 4,077,213 issued on March 7, 1978, to Glenn E. Hagen and U.S. Pat.No. Re. 31,111 of Dec. 28, 1982, issued to Glenn E. Hagen.) However,such electrical equipment is expensive, both in initial and maintenancecosts.

Another concept would be to skip the electrical step and use the motionof floats on the surface of the sea to pump water vapor in apressure-difference still. The temperature of the ocean's surface in thearea of the Virgin Islands is about 33 degrees C. At that temperature,water will boil if subjected to a vacuum of about 30 millimetersabsolute. This suggests that wave-powered cylinders could be used tocreate a 30 millimeter vacuum and allow the sea water to boil from theheat of the ocean. Unfortunately, steam at this low pressure is not verydense. It would take enormous cylinders to distill a practical amount offresh water. This arrangement would be both economically and physicallyimpractical.

It is an object of the present invention to provide a system fordistilling sea water and other impure aqueous solutions through the useof wave energy.

It is another object of the present invention to provide a scheme fordistilling sea water at relatively high temperatures and pressureswithout generating or needing electricity.

It is still another object of the present invention to provide a seawater distillation apparatus and method that is economically competitivewith oil-fired stills.

It is a further object of the present invention to provide a techniquefor extracting wave energy which maximizes the vacuum imparted to thesystem per passing wave.

These and other objects and advantages of the present invention willbecome apparent from a reading of the attached specification andappended claims.

DISCLOSURE OF INVENTION

The present invention provides a system for the distillation of impureaqueous solutions, particularly sea water, comprising: a sea water inputconduit, an evaporator communicating with the sea water input conduit, awork extracting device responsive to the wave motion of a body of waterand communicating with the evaporator, a condenser communicating withthe work extracting device, a distilled water output conduitcommunicating with the condenser, and a brine solution output conduitcommunicating with the evaporator. The sea water input conduit deliverssea water from a source to the evaporator. The evaporator operates undera partial vacuum so as to cause the sea water to exceed itsClausius-Clapeyron equilibrium point, thereby causing a portion of thesea water to evaporate. The work extracting device receives theevaporated portion of the sea water and serves to apply a compressivepressure upon this evaporated portion. The condenser receives thecompressed evaporated sea water from the work extracting device andserves to convert the evaporated portion into a liquid state. Thedistilled water output conduit removes the fresh water from thecondenser. The brine solution output conduit removes the non-evaporatedportion of the sea water from the evaporator.

The work extracting device comprises a first float, apiston-and-cylinder arrangement and a second float. Thepiston-and-cylinder arrangement comprises a cylinder, a piston slideablyengaging the interior of the cylinder and a piston rod extending fromthe piston. The piston rod couples from the first float such that thepiston moves within the cylinder in relation to the wave motion impartedto the first float. The second float is connected to the first float soas to maintain both floats in position relative to one another whileallowing these floats to move in response to the wave motion. Thecylinder is pivotally mounted to the second float. Thepiston-and-cylinder arrangement also includes check valves forpermitting the unidirectional flow of fluid into and out of the cylinderin response to the motion of the piston within the cylinder.

The evaporator is generally adjacent to the condenser such that the heatdeveloped in the condenser is transferred to the evaporator. Theevaporator also includes a pump for extracting the non-evaporated seawater therefrom. This pump communicates with the brine solution outputconduit.

A heat exchanger is also included within this system for transferringthe heat from the output of this system to the input of the system. Theheat exchanger communicates with the sea water input conduit, thedistilled water output conduit and the brine solution output conduit.

A supercharger may be connected to the sea water input conduit so as toextract energy from the sea water going into the evaporator and passingfrom the condenser. This supercharger comprises a hydraulic motoroperatively connnected to the distilled water output conduit and thebrine solution output conduit. It also comprises a pump operativelyconnected to the sea water input conduit. The hydraulic motor serves todrive the pump in the supercharger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematical representation of the distillation system of thepresent invention.

FIG. 2 is a schematical representation of the supercharger of thepresent invention.

FIG. 3 is a partial cross sectional view in side elevation of the workextractor of the present invention. This shows the work extractor in itsintermediate position.

FIG. 4 is a partial cross sectional view in side elevation of the workextractor of the present invention. This view shows the operation of thework extractor in relation to the wave motion.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, there is shown at 10 the system for thedistillation of impure aqueous solutions, namely sea water. This seawater distillation system includes a sea water inlet conduit 12, anevaporator 14, a work extraction device 16, a condenser 18, a freshwater outlet conduit 20, and a brine solution outlet conduit 22. Each ofthese elements interact so as to separate the fresh water from seawater.

Sea water inlet conduit 12 transfers the sea water from some source,such as an ocean, and delivers it to evaporator 14. A heat exchanger 24is interposed between the source of sea water and evaporator 14. As willbe described hereinafter, heat exchanger 24 serves to raise thetemperature of the incoming sea water. The sea water is received bychamber 26 of the heat exchanger. The sea water passes from chamber 26through a pipe 28 to the evaporator 14. A metering valve 30 occurs alongpipe 28. This metering valve 30 serves to maintain the level of seawater in the evaporator 14 at the proper height. Metering valve 30 maybe float-controlled (not shown) so as to maintain the liquid level atits proper height. Metering valve 30 can be adjustable to permitdifferent flow rates into the evaporator depending upon the requirementsof system 10.

Evaporator 14 receives the sea water from conduit 12 through opening 32.Evaporator 14 is a chamber that is maintained under a partial vacuum.The combination of the heat of the entering sea water along with thepartial vacuum causes the sea water to evaporate. In other words, thisarrangement causes the sea water to exceed its Clausius-Clapeyronequilibrium point and, thus, causes the sea water to become partiallygaseous. The evaporated portion of the sea water passes from evaporator14 through opening 34 toward the work extracting device 16. Thisevaporated portion will pass through line 36, through check valve 38,and into the accumulator 40 of the work extracting device. Check valve38 is of the type which will permit only the unidirectional flow offluid from the evaporator to the accumulator. The remaining brinesolution 42 within evaporator 14 is drawn by pump 44 from the evaporator14 through opening 46 and tubing 48. Brine solution 42 is the remainingimpure aqueous solution which is left after the fresh water isevaporated therefrom.

The pump 44 is a wave-powered cylinder. Such a pump is generallydescribed by U.S. Pat. No. 4,309,152 issued on Jan. 5, 1982, to Glenn E.Hagen. This pump 44 receives the brine solution 42 and transmits itthrough conduit 50 to heat exchanger 24. The brine solution 42 passesfrom conduit 50 into chamber 52 of the heat exchanger 24. Chamber 52 ofthe heat exchanger is adjacent chamber 26 such that the heat of thefluid in chamber 52 is transmitted so as to warm the sea water withinchamber 26. The brine solution 42 exits the heat exchanger chamber 52through opening 54 and brine solution outlet conduit 22. The remainingbrine solution may be stored for other purposes or may pass to anelectrolyzer, to be described hereinafter.

The work extraction device 16 is more specifically shown in FIGS. 3 and4. This work extracting device comprises a piston-and-cylinderarrangement 60, a first float 62, and a second float 64. Thepiston-and-cylinder arrangement 60 has a piston 66 slideably engagingthe interior of cylinder 68. An appropriate O-ring seal 69 is placedinto a notch about the diameter of piston 66 and interposed between thediameter of piston 66 and the interior of cylinder 68. This O-ring seal69 serves to maintain a fluid-tight seal about the interior of cylinder68. Piston rod 70 is affixed to and extends from piston 66. Piston rod70 extends outwardly from cylinder 68 and is pivotally connected atpoint 72 to the first float 62. Point 72 occurs on arm 74 extending fromfirst float 62. Cylinder 68 is yoke-mounted in pivotal fashion aboutpoint 76 of second float 64. The piston rod 70 is coupled to the firstfloat such that the piston 66 will reciprocate within cylinder 68 inrelation to the wave motion imparted by wave 78 onto first float 62.First float 62 and second float 64 are connected to each other so as tomaintain each of these floats in position relative to one another whileallowing first float 62 and second float 64 to move in response to thewave motion. First float 62 and second float 64 may be part of a Hagenarray of floats. Such a Hagen array comprises a plurality of differingsized floats with each of the float sizes chosen to allow the floats todynamically couple to the wave length of the wave motion. This type ofHagen array is described in greater detail in U.S. Pat. No. 4,077,213and U.S. Pat. No. Re. 31,111.

The method of mounting work extraction device 16 offers a number ofadvantages relative to the receiving of and use of wave energy. First,this method of mounting insures that piston 66 bottoms out against thehead of cylinder 68 in the middle of each stroke. This action ofbottoming out causes the high vacuum necessary to start the process ofthis invention. Secondly, through this method of mounting, thisbottoming out occurs regardless of the amplitude of the impinging wave78. Finally, this method of mounting yields a proportional extraction ofenergy. The yoke-mounting method is such that only a small resistance isoffered against small-amplitude waves, while a high resistance, andresulting high energy extraction, is in effect for higher amplitudewaves.

The evaporator portion of the sea water flows into accumulator 40 of thework extraction device 16. Accumulator 40 is the area formed between end80 of cylinder 68 and bottom 82 of piston 66. The evaporated portion ofthe sea water is drawn from evaporator 14 into accumulator 40 throughthe motion of the piston 66, as shown in FIG. 4. The first float 62reacts to waves 78 such that arm 74 of first float 62 pulls the pistonrod 70 away from end 80 of cylinder 68. When the first float returns toa neutral or level position, as shown in FIG. 3, piston 66 bottoms atend 80 of cylinder 68. When the piston 66 bottoms against end 80, theevaporated portion of the sea water is forced through check valve 84 andinto line 86. This evaporated portion then flows through opening 88 intocondenser 18. The compression of the steam within the cylinder heats thesteam and causes it to return to the condenser at a higher temperaturethan when it left the evaporator. The temperature of the evaporatedportion within condenser 18 serves to transfer heat to evaporator 14. Asstated previously, evaporator 14 and condenser 18 are adjacent to eachother such that any elevated temperature about condenser 18 istransferred to evaporator 14. The evaporated portion passes fromcondenser 18, through pipes 90, and into chamber 92 of heat exchanger24. It should be noted that the interaction of condenser 18 and heatexchanger 24 causes the evaporated portion to become transformed intoits fresh water liquid state. In other words, the evaporated portion isbeneath its Clausius-Clapeyron equilibrium point. This causes thesteaming evaporated portion to condense into a liquid. Since chamber 92of heat exchanger 24 is adjacent to chamber 26 of the heat exchanger,the cooler temperature of the sea water within chamber 26 will assist incondensing the evaporated portion. Similarly, the higher temperature ofthe evaporated portion with chamber 92 will serve to increase thetemperature of the sea water within chamber 26. The resultant freshwater exits chamber 92 through water outlet conduit 20. The fresh waterflowing through the system may be accumulated in a fresh water reservoiror may pass to an electrolyzer, to be described hereinafter.

The operation of the system of the present invention is describedhereinafter. While this is a continuous flow system, the operation willbe described from an imaginary start point. The sea water flows fromsome source through conduit 12 into chamber 26 of heat exchanger 24.Chamber 26 is surrounded by hot chambers 52 and 92. Chambers 52 and 92serve to bring the temperature of the sea water to a temperature onlyslightly cooler than 100 degrees C. The now-warmed sea water passes fromchamber 26 through pipe 28 and into evaporator 14. Evaporator 14 ismaintained in a partial vacuum such that the sea water is caused toexceed its Clausius-Clapeyron equilibrium point. When the present systemis in equilibrium, the evaporator is only slightly cooler than 100degrees C. and its pressure is only slightly less than atmospheric. Theevaporator 14 causes the sea water to boil, thereby creating anevaporated portion. The evaporated portion is drawn into accumulator 40of piston-and-cylinder arrangement 60 through the wave motion acting onfirst float 62. This motion is shown in FIG. 4.

When incoming wave 78 lifts first float 62 toward its crest position,the arm 74 swings downward, tipping the cylinder 68 upward into theposition shown in FIG. 4, and pulling out the piston rod 70. Thisoperation creates the suction stroke of the work extracting device.Steam is thereby drawn in through check valve 38. In this arrangement,it does not matter where the suction stroke terminates; the importantthing is that it starts from zero volume and can therefore create ashigh a vacuum as necessary to cause the sea water to boil. This actionof piston-and-cylinder assembly creates the partial vacuum withinevaporator 14. As the wave crest subsides, the float 62 returns to itsneutral postion, as shown in FIG. 3, thereby forcing the piston rod into form the compression stroke. Then, as the wave trough arrives, thefloat 62 will be dropped downward, the cylinder tipped downward and aresultant suction stroke is created. This action is enhanced by theability of the cylinder to pivot about second float 64. After thissuction stroke, another compression stroke is created as the float 62rises back to its neutral postion. In this arrangement there are twocompression strokes to each full wave cycle.

On the compression stroke, the piston 66 transfers almost an entirecylinder of steam from the evaporator 14 to the condenser 18. This steamexits through check valve 84, through line 86, and into condenser 18. Inthis arrangement, the cylinder is doing the work on the system. At thestart of the compression stroke, the steam is being adiabaticallycompressed from the evaporator vacuum up to atmospheric. This heats thesteam, so that it returns to the condenser 18 at a higher temperaturethan it leaves the evaporator 14. This increase in temperature is heldcaptive by the heat exchanger. In other words, as the brine solution andfresh water condensate become hotter, the incoming sea water also getshotter. As a result, the pressures and temperatures both increase untilan equilibrium is reached where the evaporator is only slightly coolerthan 100 degrees C. and its pressure only slightly less thanatmospheric. The entire system operates without the need for electricalinput.

The fresh water flows from the heat exchanger 24 through fresh wateroutlet conduit 20. This fresh water may be put to any useful purpose, asdesired. The brine solution that remains is pumped by pump 44 fromevaporator 14 outwardly through heat exchanger 24 and through brinesolution outlet conduit 22. Since pump 44 is similarly wave driven,there is no need for electrical power to operate this pumping system.

An addition to this system which further facilitates its practicality isthe addition of a supercharger, as shown schematically in FIG. 2. Thissupercharger assists in extracting energy from the sea water going fromatmospheric pressure into the vacuum from the evaporator 14 and from thefresh water going from the pressure of the condenser 18 down toatmospheric pressure. This extracted energy may then be used to powerpump 44 so as to remove the brine from the vacuum of the evaporator. Inthe embodiment as shown in FIG. 1, at the right hand end of the heatexchanger 24, the input and output are at atmospheric pressure. FIG. 2shows the arrangement of motors and pumps for extracting energy.Specifically, pump 44 is operatively connected to the brine solutionoutlet conduits 48 and 50. Hydraulic motor 102 is operatively connectedto the fresh water outlet conduit 20. Hydraulic motor 104 is operativelyconnected to the sea water inlet conduit 12. The movement of the seawater into the system and the fresh water out of the system serves todrive hydraulic motors 102 and 104. The hydraulic motors, in turn, drivea pump 44 for the removal of the brine solution from the vacuum of theevaporator.

This system should run itself with energy to spare. For example, iftwo-thirds of the incoming seawater is to be evaporated, then the brineto be pumped out will be only one-third the volume of the incomingseawater driving the motor. In addition, since the condenser is at apositive pressure from the start, the fresh water exiting can drive thesecond motor 102 so as to further help make pumping systemself-energizing.

In summary, the system of the present invention has a wide variety ofadvantages and uses. It is very effective as a means for distilling seawater. The system is cost effective and efficient. Since it is a closedsystem, there is no need for external energy input (other than themotion of the waves of a body of water).

The foregoing disclosure and description of the invention isillustrative and explanatory thereof, and various changes in the methodsteps as well as in the details of the illustrated apparatus may be madewithin the scope of the appended claims without departing from the truespirit of the invention.

I claim:
 1. A work extracting device driven by the wave motion of afluid, said wave motion having an amplitude spectrum and a wave lengthspectrum comprising:a first float having a density such that said firstfloat floats in said fluid and moves in response to said wave motion; acylinder; a piston slideably engaging the interior of said cylinder; apiston rod fastened and extending from said piston; and a second floatconnected to said first float so as to maintain said first and saidsecond floats in position relative to one another while allowing saidfirst and second floats to move in response to said wave motion, saidcylinder being pivotally mounted to said second float, said first floathaving an arm fixedly connected to and extending longitudinally fromsaid first float a distance beyond the point of connection between saidfirst float and said second float, said piston rod pivotally connectedabout the end of said arm of said first float, said end of said armbeing opposite said first float and beyond the point of connectionbetween said first float and said second float.
 2. The device of claim1, said device further comprising:work receival means connected to saidcylinder for transferring the energy of the movement of said pistonwithin said cylinder.